6. The Taxonomic Hierarchy

Classification involves a hierarchy of steps, where each step represents a rank or category. All categories together constitute the taxonomic hierarchy. As one moves up the hierarchy from species to kingdom, the number of common characteristics decreases.

• Species: The lowest category. It is a group of individual organisms with fundamental similarities. Members of one species can be distinguished from other closely related species based on distinct morphological differences.
• Genus: Comprises a group of related species that share more common characters compared to species of other genera. It is an aggregate of closely related species. (e.g., the genus Panthera includes species like leo (lion), pardus (leopard), and tigris (tiger)).
• Family: A group of related genera with fewer similarities than a genus or species. Families are characterized by both vegetative and reproductive features in plants. (e.g., the family Felidae includes the genus Panthera and the genus Felis (cats)).
• Order: An assemblage of families exhibiting a few similar characters. The similarities are less than in a family. (e.g., Order Carnivora includes families like Felidae and Canidae).
• Class: Includes related orders. (e.g., Class Mammalia includes Order Primata (monkey, gorilla) and Order Carnivora (tiger, cat, dog)).
• Phylum / Division: A higher category comprising related classes. In animals, it is called Phylum (e.g., Phylum Chordata includes classes like fishes, amphibians, reptiles, birds, and mammals). In plants, it is called Division.
• Kingdom: The highest category. All animals are placed in Kingdom Animalia, and all plants are placed in Kingdom Plantae.

Organisms with their Taxonomic Categories